The present invention deals with chromatography. More specifically, the present invention deals with a modular gas chromatograph formed as an easily replaceable module.
Gas chromatographs are used to measure various gas species in a gas sample. A portion of the gas sample is received at an inlet of the gas chromatograph. The gas sample is moved through a column which has an interior that is lined with one of any number of known materials, depending on the particular application or gas chromatograph being used. The column separates the larger and smaller molecules in the gas sample. Thus, the gas sample exits the column in such a manner that the first gas species out of the column is the one with the smallest and lightest molecules (a typical example is helium), while the last species is the one with the largest and heaviest molecules. The length of the column varies with each application. Typically, however, where there are a large number of species which the chromatographer desires to separate out from a single gas sample, the column must be quite lengthy.
The gas exiting the column is directed to a detector which detects the various gas species in the sample, as they exit the column. The detector, in turn, provides an output signal indicative of those gas species.
Conventional gas chromatographs include valves, detectors, piping, and heaters, all combined with various fittings, screws and connectors. These devices are all connected to one another in a manner which makes them difficult to repair and disassemble.
Further, different columns must be used for different applications. It is so difficult to change columns in present gas chromatographs, that this is very seldom done. Instead, different gas chromatographs are configured to test for different gas species or are configured to operate in different applications.
In addition, different types of chromatograph configurations require different valve configurations. For example, two known chromatograph configurations are a stripper configuration and a backflush configuration. These two require valves to be configured in a different manner. It is difficult to change valve configurations in conventional gas chromatographs.